1. Technical Field of the Invention
The present invention relates in general to message routing in mobile telecommunications systems, and in particular to the provision of addresses for use in different signaling systems.
2. Description of Related Art
Many cellular telephone networks support the transmission of short message service (SMS) messages between short message entities, including mobile stations and short message terminals. The purpose of a short message service is to provide a means for transferring textual messages between the short message entities using the communications environment provided by a cellular telephone network.
Generally, such short message service messages originate with or terminate at a subscriber mobile station. In particular, an SMS message is delivered from an originating short message entity to an SMS message center via a fixed telephone network and/or a cellular telephone network. The message center serves as a store and forward center for receiving and delivering SMS messages to a destination short message entity. Upon receiving an SMS message intended for the destination short message entity, the SMS message center attempts to forward the message to that entity. If the attempt fails, the SMS message center stores the message for subsequent delivery to the destination short message entity. The HLR will notify the SMS message center when the subscriber is again active (i.e., registered) in the network. At that time, the SMS message center can again attempt to deliver the SMS message to the destination short message entity. It would be preferable, however, if the SMS system were designed to provide reliable message delivery by decreasing the amount of failed delivery attempts.
During normal cellular operations, mobile stations periodically register with a visited mobile switching center (VMSC) that serves the area in which the mobile station is currently located. Using information contained in the registration signal, the VMSC notifies a home location register (HLR) associated with the subscriber mobile station of the mobile station""s current location. The location information is stored in the HLR and can subsequently be used in any of a variety of circumstances in which the mobile station needs to be contacted, such as when a call directed to the mobile station is received by the cellular network.
Delivery of SMS messages is another situation in which the stored location of the mobile station is used. When an SMS message center receives an SMS message to deliver to a cellular subscriber, it must request the SMS address of the destination cellular subscriber from the HLR associated with the subscriber. Once the HLR provides the SMS address, the message center uses the received SMS address for routing the message to the mobile station.
In some cases, however, the SMS message center can not recognize the format of the SMS address provided by the HLR. In particular, in current systems, the SMS address type or format that is provided by the HLR matches the type of signaling system used for communications between the VMSC and the HLR. This signaling system is not necessarily the same as, or compatible with, the signaling system used by the message center for delivery of the SMS message. If these signaling systems, or their respective SMS address types, are incompatible, the message center can not deliver the message.
Similarly, for international roaming operations (i.e., when a mobile station registers in a country other than the country in which the mobile station""s HLR is located), the foreign cellular network might use a signaling system that is not compatible with the signaling system used in the mobile station""s home country. Such an incompatibility might prevent communications between cellular telecommunication nodes in the home country and in the foreign country. For example, the VMSC in the foreign country might not be able to route messages to the gateway MSC (GMSC) in the mobile station""s home country.
There is a need, therefore, for a method and system for facilitating communications between networks, or nodes within a network, that use different address types or formats or different signaling systems. Such a method and system would decrease the potential for failed communication attempts and would avoid the subscriber inconvenience caused by such failed communications attempts. Furthermore, such a method and system would increase the attractiveness of the SMS feature and would expand the territory in which cellular subscribers can use their mobile telephones.
The present invention comprises a method and system for providing access to a mobile station in a telecommunications system that includes networks that use incompatible common channel signaling systems. In accordance with the invention, an address for a serving mobile telecommunication node where the mobile station is currently located is provided to an originating telecommunication node from which an access to the mobile station is attempted.
In accordance with one embodiment of the present invention, current location data for the mobile station is stored in a database. Subsequently, a request for an address for use in delivering a short message service (SMS) message is received. It is determined, however, that the stored location data for the mobile station is incompatible with a signaling system to be used for delivering the SMS message. Accordingly, a physical address that corresponds to the current location data and that is compatible with the signaling system is identified and is used for delivering the SMS message via the signaling system.
In accordance with another embodiment of the invention, a mobile station registers with a serving telecommunication node, which sends location data for the mobile station to a database associated with the mobile station. The location data is transmitted via a first signaling system and is stored in the database. Subsequently, a request for a current location of the mobile station is received from a telecommunication node that is attempting to access the mobile station.
In one embodiment of the invention, the attempted access involves an attempt to deliver an SMS message using a second signaling system, wherein addresses that are compatible with the first signaling system are not compatible with the second signaling system. In response to the request for the current location, at least a portion of the stored location data is retrieved from the database for use in connection with the attempt to deliver the SMS message to the mobile station. Because the SMS message is to be delivered using the second signaling system, however, a physical address that is compatible with the second signaling system needs to be identified. Once such a physical address is identified, the SMS message can be delivered using that physical address by transmitting the SMS message via the second signaling system.
In another embodiment of the invention, the attempted access involves an attempt to set up an international call connection from the telecommunication node that is attempting to set up the call connection to the mobile station. In this case, it is assumed that the originating telecommunication node uses a second signaling system for transmitting signaling messages. In response to the request for the current location, at least a portion of the stored location data is retrieved from the database for use in connection with subsequent messaging towards the destination. Because the originating telecommunication node uses the second signaling system, however, a physical destination address that is compatible with the second signaling system needs to be identified. Once such a physical address is identified, the physical address is delivered to the originating telecommunication node, and subsequent cellular protocol messages are transmitted via the second signaling system using the identified physical address.
In yet another embodiment of the invention, the serving mobile telecommunications node receives a physical address for the originating telecommunications node that is compatible with the second signaling system, which is used by the originating telecommunications node. Because the serving mobile telecommunications node uses the first signaling system, however, a physical destination address that is compatible with the first signaling system needs to be identified so that the serving mobile telecommunications node can communicate with the originating telecommunications node. The identified physical address is used by the serving mobile telecommunications node for transmitting subsequent cellular protocol messages to the serving telecommunications node via the first signaling system.